我国江淮和黄淮地区强对流过程的基本特征

中国江淮和黄淮地区是强对流天气多发区域，利用2010-2012年（4-10月）常规观测资料和再分析资料，对江淮和黄淮地区（30°N~37°N，110°E~122°E）发生的418个强对流天气过程进行了统计分析，得到该地区强对流发生的时空特征、典型环境背景以及对流关键参数的统计特征.统计发现，江淮和黄淮地区强对流天气主要发生在6-9月，8月最多，呈单峰型.空间上，江淮和黄淮地区有明显的3块强对流多发区域，分别是山东泰山周边地区、东部平原地区、大别山和黄山一带，其中发生在东部平原区域的强对流过程所占比例最高，达到了35.3%.从日变化来看，强对流主要发生在15：00-21：00（LST，下同），其次是06：00-09：00，呈双峰型，并且在空间走势上从早至晚呈自西北向东南的发展规律.根据500 hPa形势场将个例分成低槽型、副高型、冷涡型、台风型4大类，其中低槽型284例，副高型101例，冷涡型16例，台风型17例.由探空数据统计发现，副高型水汽更多集中在边界层低层，而台风型水汽更多分布在深厚的对流层中，低槽型水汽条件适中，冷涡型最小且抬升凝结高度最高；副高型最不稳定，低槽型适中，冷涡型不稳定度最低.通过与已有研究对比，本研究区域的强对流过程潜在不稳定度较小，但具有较湿的环境场.

General characteristics of the convection weather processes over Jianghuai and Huanghuai region

There is a high frequency of severe convective weather occurring in Jianghuai and Huanghuai region of China. Based on the conventional observation data and NCEP reanalysis data from 2010 to 2012 (April to October), the spatial distributions and the temporal variability, the typical synoptic weather environments and the statistical characteristics of key parameters of 418 convective events over Jianghuai and Huanghuai region (30°N-37°N,110°E-122°E) are investigated. Results show that severe convective events mainly occur from June to September with a single-peak in August. Three areas are identified as high frequency of occurrence of severe convective events. The most favorable area of the severe convective events is the plain of East China with an occurrence frequency of 35.3%. The other two areas are around Dabie Mountain and Huangshan Mountain and near the southern boundary of Tai Mountain, respectively. Their diurnal variations show a major peak in the late afternoon(15:00-21:00, LST)and a second peak in the morning (06:00-09:00,LST). The largest frequency region of severe convections occurs shifts gradually from the northwest to the southeast in Jianghuai and Huanghuai region from morning to evening. The related environmental conditions are classified into four major groups based on their 500 hPa synoptic weather maps:Trough (TR,284 cases), subtropical high (STH,101 cases),cold vortex (CV,16 cases),tropical cyclone (TC,17 cases). The composite of rawinsonde analyses show that the TC pattern features the largest moisture in the troposphere while the STH is associated with rich moisture in the lower layer. The TR has moderate moisture whereas the CV is the driest with the lowest lifting condensation level pressure (LCLP)comparatively. From the condition of instability point of view, the STH has the largest unstable condition while the TR is moderate and the CV has the lowest unstable condition comparatively. Compared to the previous studies, the severe convection weather processes in the area investigated in the current study tend to form in a moister environment and with a background of comparable moderate unstability.